Means for operating handsaws



Sept. 15, 1925.

C. JENSEN MEANS FOR OPERATING HANDSAWS Filed Sept. 2. 1924 A w N INVENTOR Cl/ZYVLSEN A TTORNEYS MHZ,

Patented Sept. 15, 1925. i 1

UNITED STATES P ATENT OFFICE.

oAnL JENSEN, or ammo; iLL-nvors.

Application filed. September To all whom it may concern:

Be it known that I, CARL Jinvsnn, a citi zen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented a new and useful 1mprovement in Means for Operating Handsaws, of which the following is a full, clear, and exactdescription.

lt is a well known fact that each time the direction of motion of a given body is re versed, the resistance opposed by its inertia has, of course, to be overcome anew, thus making the loss of energy the greater as the change of direction is more frequent. It has been found that by using springs so connected to the moving body as to be compressed and expanded by this body the body will yield a considerable surplus of power with the same expenditure of energy when the body is reciprocated so as to oscillate the same number of times as the period of oscillation of the springs.

The principal object of my invention is to provide a means for operating hand saws in which the reciprocating member is connected to the saw by means of springs and in which this reciprocating member is tuned to the normal vibration period of the spring so as to cause the member to exert the smile force upon the saw at all times and also provide a member which yields a considerable surplus of power with the same expenditure of energy, due to this special construction.

A further object of my 'nvention is to provide a means foroperating hand saws which is portable and in which saws of various kinds may be quickly attached to the device for use.

Other objects and advantages will appear in the following specification, and the novel features of the invention will be particularly pointed out in the appendedclaim.

My invention is illustrated in the accompanying drawings forming a part of this application, in which:

Figure 1 is va vertical section of the device, portions being shown in elevation, and

Figure 2 is a top plan view of a portion of the device.

In carrying out my invention I provide a casing 1 which in the present form of the device is cylindrical, and which is provided with a compartment 2 in which a motor 3 is housed. n the present form of the device I have shown the motor 3 as being of the MEANS roe ornnn'rnve wall of the cylinder by means The plunger The means end when the end of the coil spring sertedin an opening 17 in spring nannsawsn 2,-1924. Serial N02 735,467.

electrical type, although various kinds of motor power may be used without departing from the spirit and scope of the invention. A. plunger 4: is slidably mounted .in the. cylinder 1 and is spaced from-the inner of flanges 5 and 6. The space formed by the walls of the cylinder 1 and the plunger a receives a coiled spring 7, the ends of the spring being adapted to bear against the flanges 5 and 6. 4: is also provided withtwo annularly disposed ribs 8 and 9 against which portions of the coil spring 7 bear. The cylinder 1 is provided with an inwardly extending rib 10 that has grooves 11 therein to receive the spring The free end of the cylinder 1 has an inwardly extending flange 12which slidably engages with the outer surface of the plunger 4. p g

From the construction thus far described it will be apparent that the plunger is adapted to reciprocate, in the cylinder 1, and that the spring 7 tends to return the plungor to normal position and to prevent the initial movement of the plunger. in either direction from normalposition. The special purpose of the spring 7 will be hereinafter more clearly described. is

for reciprocating the plunger 3 as heretofore stated,

1 comprises a motor a crank 13, and a connecting rod 1 1. The connecting rod 1 1. 1S connected to a "coil spring 15 at the midpoint of the latter. One

of the coil spring 18. tition 16 thatextends across the cylinder 1 15 is inr the side of the 8 is carried by the free rod 1 1, and is pro- 19 that bear against plunger 4L. A block end of the connecting vided with trunnions the coils of the spring. 15. It is obvious that the connecting rod 1 1 may be connected to the spring15 in any other well known manner. The principal purpose is to connect the connecting ,rod 14 to the center of the spring 15 whereby it will be necessary to slightly compress either half of the coil 15 and to expand the other half before the connecting rod will move the plun- 'er i.

D It will be noted from Figure 2 that 1 provide a plate 20 which is secured to the plunger 4: at its free end, this plate being adapte to carry saws 21. The saws 21 have strips 22 secured thereto, this strip being provide with openings through hich bolts 23 may secured to a par too extend. The bolts 23 are inserted through pressing the portions Band C, thus storing openings in the plate and thus lock the up energy in these portions of the spring, saw 21 to the plate 20. y special type of "which energy will be expended when startsaw 21 may be used and may be substituted ingthe plunger on its reverse movement. for the saw being used bymerely removing It will clearly be seen from the forethe bolts 23 and then connecting the new saw going operation, that if the connecting rod to the plate 20 by means of ,these bolts. 14 is oscillated the same number of times as rom the foregoing description of the tie normal oscillation of the springs 7 and various parts of the device the operation 15 these springs will greatly aid in over 10 thereof may be readily understood. As coming the resistance-of inertia, thus causstated in the first part of the specification, ing the motor 3 to exert a uniform force it is necessary that the natural period of upon the saw 21,110 matter in what position vibration of the springs 7 and 15 be tuned the connecting rod 14 may be. It is ob with the number of revolutions the crank 13 vious that since this resistance of inertia is 7 to oscillate the same number of times as larger per cent of power developed by the the natural oscillation period of the springs motor 3 will be transmitted to the saw 21 and 15. Assume that the connecting rod and will not e consumed in starting and 14 is first moved in the direction as indistopping the plunger 4 as has heretofore cated the arrow in Figure 1. The trunbeen the case.

nions 19 will compress that portion of the Thecylinder l is providedwith a handle spring, hereinafter indicated by the letter 24 which may be grasped by the workman A, which extends between the trunnions and in the customary manner so as-to hold the eopeningl7, and willexpand the other porsaw in the desired position. A push button 90 25 tion B of the spring 15. Obviously the porswitch, (not shown) may be disposed adjation A will be compressed more and more cent to the handle 24, if desired, so as to peras it moves the plunger 4 in the direction nnt the operator to actuate the saw as often of the arrow. As soon as the plunger 4 as he desires. The device is extremely starts to move it will expand the portion O compact in construction, and is therefore of the spring 7 that extends between the ribs readily portable, thus permitting the device 8 and 10. It will therefore beseen that to c used as conveniently as an ordinary when the connecting rod 14 is moved in the hand saw. It is obvious that the special co-ndirection of the arrow it not only moves the struction of the moving parts will cut down plunger 4 in this direction, but also stores the troublesome vibration which is usually up energy in'the portion A of the spring 15 the case in tools which employ a reciprocatand the portion D of the spring 7. The ing member for driving. The operator can portions A and D tend to return to normal therefore use the device a long time with-. position and if permitted to dothis in their out feeling the strain that comes from graspnormal period of vibration they will give up ing a constantly vibrating handle. so their energy to the plunger 4 atthe instant I claim: 1

this energy is most needed, i. e., when the A device of the type described comprising plunger is at the end of its stroke after movea cylinder, a plunger mounted in said cylinment in the direction of the arrow. If, now, der, a spring for returning said plunger to e movement of the connecting rod is renormal position after said plunger has been versed it will not have to overcome the entire moved in either direction, a motor carried resistance of inertia, due to the fact that the by said cylinder, a crank shaft operatively portions A and D are giving up their energy connected to said motor, a connecting rod tion as the connecting rod 14 is now movin and a spring connecting said rod to said w tie plunger. During the'movement of the plunger, said rod being connected to said connecting rod 14 i areverse direction to spring midway between the ends of said the arrow, the portions and D will resume spring, said springs having a natural period their normal position and then will be ex- 0 vibration equal to the normal number of panded as the crank pin continues to move. reciprocations of said reciprocating rod. When the portions A and D are expanding, r the plunger 4 and the trunnions 19 are com I CARL JENSEN. 

